1. Field of the Invention
The present invention relates to clamping or restraining devices that are capable of being anchored or clamped within the interior of pipes.
2. Relevant Background
It is common for testing tools to be utilized for testing the integrity of pipes or welds provided on pipes. In addition, various isolation tools are known, which are used to isolate a particular section of a pipe from another. Examples of such tools are provided in U.S. Pat. Nos. 5,844,127 and 6,131,441 (the entire contents of these patents being incorporated herein by reference). In use, tools such as these are inserted within a pipe and anchored against the interior wall of the pipe. With the tools of the aforementioned patents, the anchoring step is achieved by means of bolts and the like that deform resilient annular rings such that the rings deform radially outwardly against the pipe wall. The tools, once positioned and anchored are able to withstand a high degree of displacement pressure.
Notwithstanding the anchoring force provided by the aforementioned tools themselves, it may be advisable to provide, for additional safety, a further clamp or restraint device within the pipe to restrain the tool in the event that pressure is built up adjacent the tool. As will be understood by persons skilled in the art, in situations where the pressure exceeds the anchoring force of the tool, the tool may be violently ejected from the pipe. Thus, a restraint device would offer an additional support in such circumstances.
It is also known in the art to provide internal clamps to maintain two pipes in axial alignment while welding such pipes together. Examples of such internal clamps are provided in U.S. Pat. Nos. 4,463,938; 5,816,475; and 5,875,955 (the entire contents of these patents being incorporated herein by reference). The devices described in these patents comprise complex mechanical mechanisms that are designed to be anchored against the interior walls of adjacent pipes so as to hold such pipes in abutting arrangement. A welding process can then be applied to join the pipe ends together.
Another issue faced with known internal clamping devices is that they often result in damage to the internal wall of the pipe in which they are used. That is, many of the known clamps utilize shoes that are biased against the internal pipe wall and which are provided with teeth to engage such wall. The teeth provide an added anchoring force to prevent translational movement of the device within the pipe. However, as will be understood, once the device is removed, the marks left by such teeth would result in damage to the pipe interior and in some cases lead to a region of weakness.
The devices known in the art comprise either cumbersome and/or complex mechanisms or are not easily adaptable for use with testing or isolation tools or result in damage to the pipe. Thus, there exists a need for an improved internal pipe clamp or restraint device.